Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755954AbaAWCaA (ORCPT ); Wed, 22 Jan 2014 21:30:00 -0500 Received: from mail7.hitachi.co.jp ([133.145.228.42]:51865 "EHLO mail7.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755616AbaAWC35 (ORCPT ); Wed, 22 Jan 2014 21:29:57 -0500 Subject: [PATCH -tip 4/8] perf-probe: Use the actual address instead of the symbol name To: Arnaldo Carvalho de Melo From: Masami Hiramatsu Cc: Srikar Dronamraju , David Ahern , linux-kernel@vger.kernel.org, "Steven Rostedt (Red Hat)" , Oleg Nesterov , Ingo Molnar , "David A. Long" , yrl.pp-manager.tt@hitachi.com, Namhyung Kim Date: Thu, 23 Jan 2014 02:29:55 +0000 Message-ID: <20140123022954.7206.77940.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp> In-Reply-To: <20140123022945.7206.79944.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp> References: <20140123022945.7206.79944.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since several local symbols can have same name (e.g. t_show), we need to use the actual address instead of symbol name for those points. Note that this works only with debuginfo. E.g. without this change; ---- # ./perf probe -a t_show \$vars Added new events: probe:t_show (on t_show with $vars) probe:t_show_1 (on t_show with $vars) probe:t_show_2 (on t_show with $vars) probe:t_show_3 (on t_show with $vars) You can now use it in all perf tools, such as: perf record -e probe:t_show_3 -aR sleep 1 ---- OK, we have 4 different t_show()s. All functions have different arguments as below; ---- # cat /sys/kernel/debug/tracing/kprobe_events p:probe/t_show t_show m=%di:u64 v=%si:u64 p:probe/t_show_1 t_show m=%di:u64 v=%si:u64 t=%si:u64 p:probe/t_show_2 t_show m=%di:u64 v=%si:u64 fmt=%si:u64 p:probe/t_show_3 t_show m=%di:u64 v=%si:u64 file=%si:u64 ---- However, all of them have been put on the *same* address. ---- # cat /sys/kernel/debug/kprobes/list ffffffff810d9720 k t_show+0x0 [DISABLED] ffffffff810d9720 k t_show+0x0 [DISABLED] ffffffff810d9720 k t_show+0x0 [DISABLED] ffffffff810d9720 k t_show+0x0 [DISABLED] ---- With this change; ---- # ./perf probe -a t_show \$vars Added new events: probe:t_show (on t_show with $vars) probe:t_show_1 (on t_show with $vars) probe:t_show_2 (on t_show with $vars) probe:t_show_3 (on t_show with $vars) You can now use it in all perf tools, such as: perf record -e probe:t_show_3 -aR sleep 1 # cat /sys/kernel/debug/tracing/kprobe_events p:probe/t_show 0xffffffff810d9720 m=%di:u64 v=%si:u64 p:probe/t_show_1 0xffffffff810e2e40 m=%di:u64 v=%si:u64 t=%si:u64 p:probe/t_show_2 0xffffffff810ece30 m=%di:u64 v=%si:u64 fmt=%si:u64 p:probe/t_show_3 0xffffffff810f4ad0 m=%di:u64 v=%si:u64 file=%si:u64 # cat /sys/kernel/debug/kprobes/list ffffffff810e2e40 k t_show+0x0 [DISABLED] ffffffff810ece30 k t_show+0x0 [DISABLED] ffffffff810f4ad0 k t_show+0x0 [DISABLED] ffffffff810d9720 k t_show+0x0 [DISABLED] ---- This time, each event is put in different address correctly. Note that currently this doesn't support address-based probe on modules (thus the probes on modules are symbol based), since it requires relative address probe syntax for kprobe-tracer, and it doesn't implemented yet. One more note, this allows us to put events on correct address, but --list option should be updated to show correct corresponding source code. Signed-off-by: Masami Hiramatsu --- tools/perf/util/probe-event.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 2fb4486..92ab688 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -1529,20 +1529,27 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev) if (buf == NULL) return NULL; - if (tev->uprobes) - len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s:%s", - tp->retprobe ? 'r' : 'p', - tev->group, tev->event, + len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s ", tp->retprobe ? 'r' : 'p', + tev->group, tev->event); + if (len <= 0) + goto error; + + /* Use the real address, except for kernel modules */ + if (tp->address && !(tp->module && !tev->uprobes)) + ret = e_snprintf(buf + len, MAX_CMDLEN, "%s%s0x%lx", + tp->module ?: "", tp->module ? ":" : "", + tp->address); + else if (tev->uprobes) + ret = e_snprintf(buf + len, MAX_CMDLEN, "%s:%s", tp->module, tp->symbol); else - len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s%s%s+%lu", - tp->retprobe ? 'r' : 'p', - tev->group, tev->event, + ret = e_snprintf(buf + len, MAX_CMDLEN, "%s%s%s+%lu", tp->module ?: "", tp->module ? ":" : "", tp->symbol, tp->offset); - if (len <= 0) + if (ret <= 0) goto error; + len += ret; for (i = 0; i < tev->nargs; i++) { ret = synthesize_probe_trace_arg(&tev->args[i], buf + len, -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/